The present invention relates generally to endwall flowpath surface contours for gas turbine engines, and more particularly to non-axisymmetric endwall flowpath surface contours.
Gas turbine engines are well-known, and generally include various rotating and non-rotating airfoils arranged in cascades. These airfoils include fluid working surfaces that can interact with working fluids along an engine flowpath during engine operation. Endwalls are structures that bound portions of the engine flowpath, typically at radially inner and outer locations along the flowpath. These endwalls can adjoin the airfoils. In some instances, endwalls are defined by platforms or shrouds integral to the airfoil. In other instances, endwalls are defined by structures separate from the airfoils, such as ducts, shrouds, spacers and the like.
In the past, endwalls in gas turbine engines generally had axisymmetric contours, meaning the endwall was symmetric in rotation about a central axis (i.e, cylindrical, frustoconical or toroidal). Such axisymmetric endwall contours do not always provide optimal adiabatic efficiency and flow capacity, particularly due to secondary flow effects where some of the working fluid inefficiently moves in a spanwise (i.e., generally radial) direction along the working surfaces of the airfoils (with or without swirl or vortex effects).